There are known in the prior art a great many 1,4-dihydropyridine derivatives that possess hypotensive or coronarodilating activity.
One specific prior-art 1,4-dihydropyridine derivative is 2,6-dimethyl-3,5-dicarbothoxy-4-(o-trifluoromethylphenyl)-1,4-dihydropyrid ine known as SKF-24260 (see U.S. Pat. No. 3,511,847): ##STR2##
This compound features an appreciable hypotensive activity (ED.sub.30 =0.022 mg/kg).
However, the hypotensive effect produced by said compound is of short duration.
Besides, said compound is characterized by high toxicity (LD.sub.50 =38.5 mg/kg), which makes it practically impossible to be utilized medically on a wide scale.
Another prior-art 1,4-dihydropyridine derivative is 2,6-dimethyl-3,5-dicarbomethoxy-4-(o-nitrophenyl)-1,4-dihydropyridine (see U.S. Pat. No. 3,644,627): ##STR3##
This compound is commercialized under the trade names of Adalate, Corinfar, and Nifedipine. It features high coronarodilating activity coupled with low toxicity, which assures it a wide field of application in medical practice.
However, this compound is highly sensitive to light, decomposing rapidly in the presence of light.
A further 1,4-dihydropyridine derivative known to the prior art is 2,6-dimethyl-3,5-dicarbomethoxy-4-(o-difluoromethoxyphenyl)-1,4-dihydropyr idine (see U.K. Pat. No. 2,013,186): ##STR4##
This compound is known under the trade name of Ryosidine.
Said compound features effective hypotensive activity (ED.sub.30 =0.024 mg/kg) and low toxicity.
However, the hypotensive action of said compound is of short duration.